The 30-year-old, who grew up in Carntyne, has his face emblazoned on dozens of posters advertising his show, Jersey Boys, by the Tube escalators.

He said: “It’s weird because you see bits of chewing gum stuck to your face.

“And to get all four of us on the poster they had to superimpose legs on us -- they cut our own legs off. And there was one before that, where they used my left leg twice.”

Gum and wrong legs aside, it has been an amazing a year for Stephen, whose mum and dad Evelyn and Derek, both 53, and sister Stacey, 25, a Ryanair cabin crew member, live in Condorrat, near Cumbernauld.

As well as starring as one of the four leads in the musical, a show that tells the tale of 1960s band Frankie Valli And The Four Seasons, in September he was chosen to sing with Sir Elton John at a charity concert at the Royal Albert Hall.

He performed a song from Sir Elton’s vampire-inspired Broadway musical, Lestat, with the maestro on piano.

Stephen said: “It was brilliant. You walk out there and you can’t help but look up because it’s such a massive space.

“Then I got to go and sit in the Royal Box for the second half. I was sitting beside the Duchess of Gloucester. Every time she left to powder her nose everyone had to stand up. Annie Lennox and Katherine Jenkins were also in there.

“My parents also came down but had to sit with the commoners -- I gave them my royal wave from the Royal Box!”

Many celebritiess have been among the million people who have seen Jersey Boys, which Stephen will be in until March 2011.

He said: “We just had David and Victoria Beckham in with their whole family -- there were 23 of them, their boys and their parents on a Christmas outing. They had been before and we had a quick meeting. They said ‘well done’ and zoomed through with their bodyguards surrounding them.”

Actor Daniel Radcliffe, who stars as Harry Potter, and comedian and television presenter Justin Lee Collins have also been in the audience this year, while footage has even been put on internet site YouTube of Stephen chatting with Cilla Black after a performance.

“She is a legend and I was a bit star struck! She was really nice.”

The former Smithycroft Secondary School pupil won an award when he was named

Best Supporting Actor in the Theatregoers’ Choice Awards in February for his part as one of the Four Seasons, Bob Gaudio.

He said: “You never really expect them but it’s always nice to get a little bit of recognition. I have it at home on a little shelf in my dining room so nobody touches it!”

Stephen, who lives in north London, has been in the musical since it opened in February 2008.

It is about the New Jersey quartet who sold 175million records worldwide and includes hummable hits such as December 1963 (Oh What A Night), Can’t Take My Eyes Off You and Sherry.

This year Stephen has appeared on Strictly Come Dancing, Paul O’Grady, Children In Need and Alan Titchmarsh to promote the show.

But anyone who thinks it is a charmed life being a West End star should think again. The graduate of Glasgow’s RSAMD performs a gruelling eight shows a week.

Although he rushed back to Glasgow to spend some time with his family, he returned to London for two Boxing Day performances.

Plus there are a few strange rules he must stick to.

“Once you have done the show you don’t want to go to sleep straight away. You go out afterwards, have a little drink and something to eat. But we’re warned by the company vocal coach not to fall asleep after having had something to eat because you get acid reflux and the next day you can’t sing as your vocal cords have been swimming around in acid.

“It’s not all glamorous!”

The Jersey Boys is currently showing at the Prince Edward Theatre in London.